A growing body of behavioral results demonstrates cross-linguistic sensitivity to the SSP (Daland et al. 2011; Berent et al. 2007; Berent et al. 2008; Jarosz to appear; Ren, Gao & Morgan 2010). These consistent findings suggest a role for prior bias in phonological learning, but recent modeling studies question this conclusion, showing that for some languages these preferences can be derived from the input (Daland et al. 2011; Hayes 2011). Building on these results and Jarosz’s (to appear) developmental findings for Polish, the present paper investigates adult Polish speakers’ sensitivity to the SSP experimentally and computationally. We report the results of an online acceptability judgment experiment focusing on initial clusters and present the results of computational simulations evaluating the ability of phonotactic models to predict participants’ ratings on the basis of the lexical statistics of Polish. Our main findings are that 1) SSP is predictive of adults’ ratings, 2) sonority projection arises in both attested and unattested clusters, 3) while phonotactic models have significant predictive value, they do not subsume the SSP preferences observed in the participants’ ratings, and 4) participants’ sonority sequencing preferences are not entirely compatible with the SSP, suggesting a combined effect of prior bias and experience.